Methods of Immutable Deployment of Persistent Relational Databases

1. A method comprising: replacing a first server of a first node a computer network configured to provide at least one service by adding a second server configured with a database system as a second node to the computer network; taking a snapshot of a first database of database files that is communicatively coupled to the first server; applying the snapshot to the second server of the second node of the computer network by attaching the snapshot of the first database as a second database to the second server and configuring the second server to match the first server; forcing a failover of the first server of the first node in the computer network to the second node with the second server in the computer network having the second database attached to maintain at least stateful aspects of the at least one service that comprise at least one selected from a group consisting of: expecting a response, tracking information, and resending a request; and switching voting to the second server of the second node of the computer network and removing the first node of the computer network when the forced failover is successful, and falling back to the first node and performing a rollback operation when the forced failover is unsuccessful.

2. The method of claim 1, wherein the adding the second server as the second node to the computer network comprises: adding the second server to a failover cluster of the computer network that includes the first node.

3. The method of claim 2, wherein the adding the second server to the failover cluster comprises: configuring an availability group to support a failover environment for a set of databases of the computer network.

4. The method of claim 1, further comprising: storing an operating system on a first storage device communicatively coupled to the computer network; and storing at least one selected from a group consisting of: database engine binary files of the database system, and database system files on a separate storage device from at least user database files of the database system.

5. The method of claim 1, further comprising: adding the second database to an availability group of the computer network and performing synchronous replication and synchronization of data from the first database to the second database using the snapshot.

6. The method of claim 5, further comprising: forcing a failover of the computer network to the second node with the second server having the second database attached when the synchronous replication and synchronization is completed.

7. The method of claim 5, wherein the second server of the second node is added to the availability group as a non-voting member.

8. The method of claim 1, wherein the attaching the snapshot of the first database as the second database to the second server comprises keeping at least the first database in a recovery mode.

9. The method of claim 1, wherein the removing the first node of the computer network comprises: removing the first node from a failover cluster and an always-on availability group.

10. The method of claim 1, further comprising: restoring using backup data when the taking of snapshot of the computer network from the first node fails.

11. The method of claim 10, further comprising: attaching the restored backup data to the second server when the snapshot fails.

12. The method of claim 1, wherein the replacing the first server by adding the second server comprises: configuring the second server with at least one selected from the group consisting of: a new version of an operating system, a new version of an application, a new version of a database engine, a software update, a software patch, and a software bug fix.